I ordered a pretty vintage dress on Etsy and upon arrival, it smelled awful. I decided to hand wash because I like to make sure I’m being gentle with my vintage garments. The water was instantly a gross dark brown. I’ve done six rounds of hand washing a soak with normal detergent and the water is still coming out filthy. The smell was also so strong that my arms smelled like it after the first couple washes. I currently have in soaking with some Oxyclean which will hopefully help, but I really want to make sure the dress is super clean because it makes me queasy thinking about how much nastiness has come out of it so far.

Any tips? The dress is black and I believe polyester (synthetic-y material for sure, not natural)